1. Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more particularly to a transreflective type LCD and a method of manufacturing the same.
2. Description of the Related Art
In the so-called information society of these days, electronic display devices are important as information transmission media and various electronic display devices are widely applied to industrial apparatus or home appliances. Recently, demand has increased for a new electronic display device such as an LCD having characteristics such as thin thickness, light weight, low driving voltage and low power consumption. Manufacturing of such LCD has been improved due to advances in semiconductor technology.
The LCD is classified as a reflective type LCD that displays an image using a first light provided from an external, a transmissive type LCD that displays an image using a second light generated by a light generating means installed therein, and a transreflective type LCD that displays an image using either the first light or the second light. The transreflective type LCD displays the image using the first light where an amount of the first light is enough to display the image and displays the image using the second light generated by consuming electricity charged therein where the amount of the first light is not enough to display the image. Thus, the transreflective type LCD reflects the first light and transmits the second light.
FIG. 1 is a plan view showing a unit pixel of a conventional transreflective type LCD. The transreflective type LCD includes a thin film transistor (TFT) substrate (not shown), a color filter substrate (not shown) and a liquid crystal (not shown) interposed between the TFT substrate and the color filter substrate. The color filter substrate faces the TFT substrate and includes RGB color pixels and a common electrode formed over the RGB color pixels.
Referring to FIG. 1, a unit pixel 50 formed on the TFT substrate of the transreflective type LCD includes a TFT 20 and a pixel electrode 10. The TFT substrate includes a plurality of data lines 31 arranged in a row direction and a plurality of gate lines 32 arranged in a column direction. Particularly, the TFT 20 includes a gate electrode 21, a source electrode 22 and a drain electrode 23. The gate electrode 21 is commonly connected to a plurality of gate lines 32 in the column direction, the source electrode 22 is commonly connected to a plurality to data lines 31 in the row direction, and the drain electrode 23 is connected to the pixel electrode 10.
The pixel electrode 10 includes a reflective electrode 12 for displaying the image by reflecting the first light and a transmissive electrode 11 for displaying the image by transmitting the second light. That is, the transmissive electrode 11 is formed to be connected with the drain electrode 23 of the TFT, and the reflective electrode 12 having a transmissive window 13 is formed on the transmissive electrode 11 to expose a portion of the transmissive electrode 11. Thus, where an amount of an external light is enough to display the image, the unit pixel 50 displays the image in a reflective mode in which the reflective electrode reflects the external light. Where the amount of the external light is not enough to display the image, the unit pixel 50 displays the image in a transmissive mode in which a light generated by a light generating means is transmitted through the transmissive electrode 11 exposed by the transmissive window 13.
In FIG. 1, reference characters “A” and “2A” represent an area (second area) of the transmissive window 13, and an area (first area) of the reflective electrode 12, respectively. Accordingly, an area of the transmissive electrode 11 exposed by the transmissive window 13 is the same as “A”. The area “A” of the transmissive electrode exposed by the transmissive window is less than the area “2A” of the reflective electrode 12. Therefore, the transreflective type LCD displays the image in the reflective mode, and further, displays the image in the transmissive mode when the external light is not enough to display the image, thereby reducing a power consumption for generating the light.
However, since the first area “2A” is greater than the second area “A”, there is a brightness difference between the reflective mode and the transmissive mode. A brightness in the reflective mode is higher than that in the transmissive mode. If the amount of the second light increases to compensate the brightness difference, the power consumption increases.
Also, in spite of forming the reflective electrode 12 to have the first area “2A” greater than the second area “A” of the transmissive electrode 11 exposed by the transmissive window 13, the first light passes through the color filter substrate at least twice in the reflective mode. In the reflective mode, the first light is incident through the color filter substrate, and then the first light is emitted through the color filter substrate after being reflected by the reflecting electrode 12. This inevitably results in a difference in a color reproducibility between the reflective and transmissive modes.